In U.S. Pat. No. 330,796, issued Nov. 17, 1885 to Harry C. McCarty, assignor of one-half to John F. Bickel, there is shown a cock having a tapered-type cock key that is provided with a transverse passageway and a port that extends through the side of the cock key and opens into the transverse passageway. This tapered key is rotatably mountd in a body having a port provided in one side thereof. In the closed position of the key, the passageway and port therein are so disposed that the passageway is disposed in coaxial alignment with the port in the side of the cock body to thereby establish a communication between the interior of an air brake hose connected to the outlet end of the cock body and atmosphere via this passageway and port in the key and the port in the cock body. Thus, the fluid under pressure in the air brake hose is vented to atmosphere via this communication when the cock key is rotated to a closed position in which communication between the interior of the brake pipe and the interior of the hose is cut off.
Many American railroads on certain of their freight cars require a cock that, when in its closed position, establishes a communication between the interior of the air brake hose connected to the outlet of the cock secured to each respective end of a brake pipe that extends from end to end of each car and atmosphere. However, the tapered-type cock key shown in the above-mentioned U.S. Pat. No. 330,796 has been largely replaced by a ball-type valve that requires considerably less maintainence by the railroads.
Accordingly, it is the general purpose of this invention to provide a ball-type cock having novel means for venting fluid under pressure from the interior of an air brake hose connected to the outlet of such a cock upon turning the handle of this cock to its closed position in which the communication between the brake pipe and the interior of this air brake hose is closed.